1. Field of the Invention
The present invention relates to a front seatbelt system for a vehicle having a double door construction in which a front door at its rear end overlaps a rear door from the outside of the vehicle and allows the rear door to open and close only while the front door remains open.
2. Description of Related Art
Front seatbelt systems of this kind are known from, for example, Japanese Unexamined Patent Publication Nos. 2-117455 and 2001-138864. The front seatbelt system disclosed in Japanese Unexamined Patent Publication No 2001-138864 is adapted to a vehicle having a double door construction in which front and rear doors open outwardly forward and rearward, respectively to form a single uninterrupted doorway to a passenger compartment, and more particularly, to front and rear seats and the front door at its rear end overlaps the rear door so as to allow the rear door to open and close only while the front door remains open. The front seatbelt system includes a seatbelt retractor installed to the rear door.
The front seatbelt system disclosed in Japanese Unexamined Patent Publication No 2-117455 is installed to a vehicle having a double door construction in which front and rear doors are pivotally mounted to front and rear hinge pillars, respectively, and each door opens and closes previous to the other. The front seatbelt system includes a seatbelt retractor installed within the rear door and having a seatbelt lock mechanism operative to lock the front seatbelt when the front seatbelt attains a specified acceleration and a lock canceling mechanism operative to put the seatbelt lock mechanism operative to lock the front seatbelt while the rear door is open with the aim of preventing a passenger sitting on the front seat from being restrained or fastened tightly in excess.
It is conceivably found to be useful for the front seatbelt system with the seatbelt retractor installed within the rear door of the double door construction to incorporate the seatbelt lock mechanism and the lock canceling mechanism therein, however, the seatbelt lock mechanism is always put inoperative while the rear door is open. In consequence, if the vehicle is driven with the front seatbelt buckled up but with the rear door not properly closed, it is impossible to restrain or secure a passenger sitting on the front seat tightly with the front seatbelt upon an occurrence of a collision of the vehicle.